bolo,
If you're hunting in FL, you need to worry about the heat much more than a lot of the lucky northerners on this site. As you know, it was close to 80 today. That said, "immediate" field dressing is relative. Don't rush so much that you end up with a pile of sand inside the carcass. Immediate is better, but an hour or so won't hurt you. I would suggest bringing some ice and stuffing a full bag inside the cavity as soon as you've field dressed it.
Don't worry about predators. We've killed most of the big ones in FL already.
You really should get the outfitters take on all this too...